Portable communication devices such as, for example, cellular phones, wireless personal digital assistants, etc. may include an amplifier connected to an antenna. The amplifier may amplify an input signal and generate an output signal that is then transmitted by the antenna. The efficiency of the amplifier is generally measured by comparing the amount of power consumed by the amplifier vs. the amount of power of the signal that is transmitted by the antenna.
To improve the efficiency of the transmitting amplifier, a predistortion loop may be used to adjust the input signal to the amplifier to achieve a desired output signal that is as linear as possible. However, conventional predistortion loops involve the use of processing of the input signal in the digital domain. Such processing may involve additional processors and/or other logic circuitry that may increase the cost and complexity of the portable communication device.
Thus, there is a continuing need for better ways to improve the efficiency or linearity of amplifiers in portable communication devices.
It will be appreciated that for simplicity and clarity of illustration, elements illustrated in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements are exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals have been repeated among the figures to indicate corresponding or analogous elements.